Sure you can. You just have to be really, really sure of yourself. And even more sure when arguing on a Rishon (so sure, in fact, that as a practical matter you can’t argue on a Rishon but in theory you can).

Sam2- R’ Elchonon said that one who argues with a rishon is a shoteh. so, in theory, ya, you could step off the curb in to oncoming traffic. And really, R’ Akiva Eiger bleibs tz”i or Hashem yo’ir eynay rather then arguing with a Tosfos. You should feel a bit our of youe league here.

the chazon ish had a shitah that you cant follow a halachah if you were m’ayain properly and disagree. He holds that you cant use any metal, even nails, to keep a succah together, even though there is a Ritva that says b’feirush that you can, and the bais yosef paskens like that ritva. i assume R’ Moshe had this shitah to some extent as well, but this isnt a universal shitah, and even if you do hold of it, it would only matter if you looked into the sugya properly, which i doubt anyone except a gadol/posek could be sure of – meaning pashtus anyone reading this is not enough of a talmid chacham to decide thathe is 100% sure that a rishon or acharon is wrong. be safe, ask your posek what to do if a shailah comes up, definitely dont argue with rishonim.

Avi K: the Gra, according to many gedolim, was on the level of rishonim. a certain gadol said he was on the Rashba’s level of learning, so thats not a ra’aya at all

First of all, “Im rishonim kimalachim anu kbnei adam, v’im heim kbnei adam anu kchamorim” basically if we are machshiv the previous generations as regular people then we are like donkeys so don’t disregard their opinion so easily. Furthermore, yes the rishonim can be wrong, if you think you have a very good svara against their shitta do some research and it’s very possible you may find another rishon who agrees with you, however the first assumption is never to assume that they are wrong. Even if you disagree and yet still think the rishon can still be right you should probably still do some research, perhaps to find out if the rishon is lshitoso etc. and try to determine what the yesod of his shitta is and what your yesod is and find the chiluk and the mechaleik. You can always say tzurich iyun :). That’s how I would approach the situation.

“the chazon ish had a shitah that you cant follow a halachah if you were m’ayain properly and disagree. He holds that you cant use any metal, even nails, to keep a succah together, even though there is a Ritva that says b’feirush that you can, and the bais yosef paskens like that ritva.”

Actually the Chazon Ish’s own sucah was NOT a “Chazon Ish scuah”. He only presented another tzad in the sugya, he didn’t argue. However the Sridei Aish writes that it was “b’rov chasidaso” that the Chazon Ish did not argue on Rishonim.

????? ??? ??”? ?”? ?”? ??? ? says we can argue on some Rishonim with proper rayos. However he rarely dose so himself.

The Yam Shel Shlomo writes in one of his hakdamos that while it’s clear that the Rishonim were bigger he’s upset people stopped arguing and says they should. Needless to say the ?? ?? ???? was not ?????.

“the chazon ish had a shitah that you cant follow a halachah if you were m’ayain properly and disagree. He holds that you cant use any metal, even nails, to keep a succah together, even though there is a Ritva that says b’feirush that you can, and the bais yosef paskens like that ritva.”

Actually the Chazon Ish’s own sucah was NOT a “Chazon Ish scuah”. He only presented another tzad in the sugya, he didn’t argue. However the Sridei Aish writes that it was “b’rov chasidaso” that the Chazon Ish did not argue on Rishonim.

????? ??? ??”? ?”? ?”? ??? ? says we can argue on some Rishonim with proper rayos. However he rarely dose so himself.

The Yam Shel Shlomo writes in one of his hakdamos that while it’s clear that the Rishonim were bigger he’s upset people stopped arguing and says they should. Needless to say the ?? ?? ???? was not ?????.

Abelleh: You can’t help arguing with rishonim and acharonim, even if you don’t say anything not first said by a rishon. There are enough disagreements that you have on whom to rely for almost any reasonable opinion (yeah, that’s almost a tautology. So sue me.) For example, let’s say you take the approach that you can’t argue with anyone earlier than you and you even have a rishon to support you, though I don’t know of any. You are then arguing against the Rambam who says you follow ?? ????? ???? ?? regardless of when he lived.

mr. coffee room: “the Gra, according to many gedolim, was on the level of rishonim. a certain gadol said he was on the Rashba’s level of learning, so thats not a ra’aya at all”

As I heard, the story was that the brisker said to his father that he heard that the gra was like the ramban, to what the father replied: chalile!!! maybe like the rashbe! (obviously these ppl – unlike us – appreciated the diference)

hachra’a is picking the one that makes the most sense, which automatically places you in disagreement with the shitos you didn’t pick. That is what the Rambam did, and what the Ramban called him out on. THis should really be part of the “how does halacha work” thread.

“The Yam Shel Shlomo writes in one of his hakdamos that while it’s clear that the Rishonim were bigger he’s upset people stopped arguing and says they should. Needless to say the ?? ?? ???? was not ?????.”

Huh? Sure it was. I think that people happen to have an easier time arguing on the Maharashal, and for this reason, but to say he wasn’t ????? is not true at all. (Are people machmir on davar gush? Are people machmir on a kli sheini that’s yad soledes bo? Do people eat milk chocolate right after chicken soup? etc. etc.)

The shach argues regularly on Rishonim, I can think of about ten places offhand. However, he is very reluctant to argue against the Bahag and the others of thart time, because they were Geonim, and they did not write their own thoughts, rather they were actually quoting Ravina and Rav Ashi (as the Shach puts it; “kol divreihem divrei kabalka”). So there is a difference between the rishonim and the Geonim.

The one who said the Gra was like the Rashba was Rav Chaim Velozoner in the Hakdamak to Sifra Dtzniusa, not the Gra himself.

According to the Rambam in the Hakdamah to the Yad, you can argue on anyone until the Gemarah (possibly this includes the Geonim, I don’t know), but as all of us know, you would need to be either very sure or very foolish to do so.

P.s.; the Chazon Ish with regard to sukkah is not arguing on anyone; he is rather quoting a minhag in Lita to be machmir for the shita of the ran and ramban AND RITVA that the maimod needs to be of something kosher for schach. So that was a misquote. However the Chazon Ish does argue on Rishnim, I can remeber one chazon ish in kilayim who argues head-on with a Ritva

If you have a difficulty with the words of a Rishon, look around to see if your issue is discussed by the Acharonim. If it is, see how they handled it. If it isn’t, chances are excellent that you don’t have a clear picture of the sugya. Your next move should be to figure out why.

Ditto for prominent Acharonim whose words are dissected by the later generations.

If my brain tells me that something a Rishon or Achron said is illogical, did I just do something wrong? If I push that thought out of my mind, does that avoid doing the wrong? Am I aloud to think that something they said was illogical but keep it to myself to avoid this Aveirah?

Remember that the Rishonim and Achronim are smarter than you and far bigger Talmidei Chachomim than you, who have gone through Kol HaTorah Kulah more times than you finished Chamisha Chumshei Torah. Then you will better be able to realize even if you think they are wrong on an issue, that they knew more, thought it through more and knew the Torah far far better than you so that it is you who is mistaken – you just can’t find the point of where you went off the rails and see how they are right. But you intuitively know they must be right even if you can’t understand how.

Just as if you, on your couch, think Albert Einstein made an elementary error in the Theory of Relativity you’re not going to come to your next course in undergraduate Physics 101 and relate to the professor how you found a mistake in Einstein’s theory.

Sam, the undergraduate in Princeton’s Physics 101 isn’t the one to find any error by Einstein 100 years later. The gedolei haphysics found it long ago. Similarly we’re not going to find an “error” by a Rishon from 600 years ago that none of subsequent gedolei Rishonim and Achronim never pointed out in the subsequent centuries.

To quote (or perhaps paraphrase) R’ Ahron Feldman: “One argues with Chazal is not a heretic, just an arrogant fool.” I think the ame can be said about most people today arguing with the Rishonim and Achronim.

DY, the Mharshal (Chochmat Shlomo Sanhedrin 52) says that that does not apply if there is no nafka mina l’dina – and does so himself. Moreover, nobody ever died from a kashia. Resolving it is not arguing but clarifying.

To quote (or perhaps paraphrase) R’ Ahron Feldman: “One argues with Chazal is not a heretic, just an arrogant fool.” I think the ame can be said about most people today arguing with the Rishonim and Achronim.

I argue that when calculating the disgonal of a triangle, you use the Pythagorean Theorem of “A^2 + B^2 = C^2” (for a right triangle).

Gavra, actually the perush is Rashbam not Rashi. he is correct that the diagonal of a five by five square is similar to that of a four by six rectangle (the former is the square root of 50 and the latter the square root of 52)). I do not understand how Tosafot made the mistake that the former is greater then the latter, especially as they know that the the area is greater. They are also very close regarding the diagonal of the four by six (the difference can be put down to a scribal error). Chazal definitely knew the Pythagorean theorem as in several places they say that the diagonal of a one by one square is 1.4.